JPH01245064A - Coating composition and usage thereof - Google Patents

Abstract

PURPOSE:To obtain the title composition for electronic material parts such as printed boards excellent in heat resistance and flexibility, by imparting, with thixotropy, a resin solution incorporated with a polyimide precursor compound with the linear expansion coefficient after curing at or lower than a specified level. CONSTITUTION:The objective coating composition with a thixotropy factor of >=3 can be obtained by incorporating (A) a polyimide precursor compound with the linear expansion coefficient after curing of <=20X10<-6> (1/K) [e.g., of formula I (R5-R12 are each H, halogen, lower alkyl or lower alkoxy, at least one of R7-R10 being lower alkoxy; Ar is of formula II or III) structural unit] with (B) at least one good solvent (e.g., N,N-dimethylacetamide) and at least one poor solvent.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to heat-resistant coatings used for coating electronic material components such as printed circuit boards, particularly flexible printed circuit boards, etc.
This invention relates to a coating composition with excellent flexibility and its use.

[Prior Art] Conventionally, circuits on flexible printed circuit boards (hereinafter abbreviated as FPC) have been protected by either laminating a coverlay film using adhesive or printing solder resist ink. ing.

However, the method of laminating a coverlay film has problems in that it requires time and effort to process and has poor dimensional accuracy, resulting in poor product yield and high manufacturing costs. Further, the method of printing solder resist ink has a problem in that although the manufacturing cost is low, it is inferior in terms of mechanical properties such as bending resistance, and its range of use is limited.

Furthermore, as a heat-resistant resin-containing composition for coating, a method is known in which spherical porous polyamide powder is blended into a polyamic acid solution modified with diaminosiloxane (Japanese Unexamined Patent Publication No. 108.068/1989). However, with this method, the obtained film has a large coefficient of linear expansion, and when used to cover an FPC, there is a problem that the FPC will curl significantly due to the difference in coefficient of linear expansion between the substrate and the protective film during curing. There is.

Furthermore, a method of adding benzylidene sorbitol to a polyimide resin precursor is also known (Japanese Unexamined Patent Application Publication No. 1983-1999).
266,650), but there is a problem that the film obtained using this method is brittle.

[Problems to be Solved by the Invention] Therefore, as a result of intensive research to solve these problems, the present inventor found that the coefficient of linear expansion upon curing was 20X 1O.
The inventors have discovered that these problems can be solved by imparting thixotropy to a resin solution containing a polyimide precursor compound of -6 (1/K) or less, and have completed the present invention.

Therefore, an object of the present invention is to provide a protective film which has a small linear expansion coefficient of 20×1O-6 (1/2) or less, and which has excellent heat resistance and flexibility. An object of the present invention is to provide a coating composition.

Another object of the present invention is to provide a coating composition that has excellent thixotropy with a thixotropy coefficient of 3 or more and has performance suitable for screen printing.

Furthermore, another object of the present invention is to form a polyimide protective film on the surface of FPC etc. easily and with good dimensional accuracy by applying a method similar to the method of printing solder resist ink, that is, screen printing technology. An object of the present invention is to provide a coating composition capable of providing a coating composition and a method for using the same.

[Means for Solving the Problems] That is, the present invention has a linear expansion coefficient of 20X 1 after curing.
This is a coating composition containing a polyimide precursor compound having a polyimide precursor compound having a molecular weight of O-6 (1/K) or lower and a thixotropic coefficient of 3 or higher.

The polyimide precursor compound referred to herein is a compound that provides a polyimide compound such as polyimide, polyamideimide, polyetherimide, polyesterimide, polysiloxane imide, etc. when cured.

In addition, the thixotropic coefficient refers to the shear of 5eC-
η1/η when the viscosity at 1 is η100
It is a coefficient defined as a value of 100 and is a measure of printing performance. If it is less than 3, there will be problems such as large drips and smearing during screen printing and large stickiness to the screen. arise.

The coefficient of linear expansion during curing is 20X 10' (1/K
) The following polyimide precursor compound is preferably one of the following - Shipman (I> (wherein R1 to R4 are each a group selected from hydrogen, halogen, lower alkyl group, and lower alkoxy group). A polyimide precursor containing a structural unit represented by the following (indicates R5 to R12
each represents any group selected from hydrogen, halogen, lower alkyl group, and lower alkoxy group, among which at least one of R7-R10 is a lower alkoxy group, and ^r represents either or ), and the most preferred polyimide precursor compound is a polyamide-imide precursor containing a structural unit represented by the following formula (■): can.

The above-mentioned compounds (I) and (n) can be easily synthesized by a polymerization reaction using diamine and tetracarboxylic acid or a derivative thereof as raw materials. Examples of the tetracarboxylic acid derivatives mentioned here include esters, acid anhydrides, acid chlorides, and the like.

That is, the compound of the above -Funenin (I>) is the compound of the following -Funenin (I>).
IV) A phenylenediamine derivative represented by (in the formula, R1 to R4 are the same as above) and 3.3', 4,4°-
It can be produced by a polymerization reaction with biphenyltetracarboxylic acid or a derivative thereof. Here, the lower alkyl group and the lower alkoxy group preferably have less than 10 carbon atoms, and if the carbon number is 10 or more, it becomes difficult to achieve low thermal expansion.

In addition, the compound represented by the above -Funenin (I[) is the following -
Saito (V) (However, R5 to R12 in the formula are the same as above) 4,4'-diaminobenzanilide derivative and pyromellitic acid or its derivative or 3.3°, 4,4° −
It can be produced using either biphenyltetracarboxylic acid or its derivatives, or even both.

Here, the lower alkyl group and the lower alkoxy group preferably have less than 10 carbon atoms, and it is difficult to achieve low thermal expansion when the number of carbon atoms is 10 or more.

Preferred examples of the 4,4′-diaminobenzanilide derivatives include 2-methoxy-4,4°-diaminobenzanilide, 2°-methoxy-4,4°-diaminobenzanilide, 2,2-dimethoxy −4,4°−
Diaminobenzanilide, 2,6-simethoxy 4.4
-diaminobenzanilide, 2,6゛-dimethoxy-4
, 4°-diaminobenzanilide, etc., and 2°-diaminobenzanilide is more preferable from the viewpoint of ease of synthesis.
-methoxy-4,4-diaminobenzanilide.

The synthesis reaction is carried out using N-methyl-2-pyrrolidone, N-methyl-2-pyrrolidone, which is a good solvent for the polyimide precursor compound for boat fishing.
, N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide, N.

0 to 20 in a solvent containing N-diethylacetamide etc.
It is carried out at 0°C, preferably in the range of 0 to 100°C. If the reaction temperature exceeds 200° C., imidization reaction may proceed during the polymerization reaction, making it difficult to obtain the low thermal expansion effect of the present invention, and also significantly reducing moldability.

The polyimide precursor compound of the present invention is the above-mentioned Funenjin (I)
> or 30 mol% or more of the structural unit represented by (II>,
Preferably it contains 40 mol% or more,
If it is less than 30 mol%, the effect of reducing thermal expansion will be small.

For other structural units, copolymerization is performed using various diamines, tetracarboxylic acid compounds, tricarboxylic acid compounds, or acid anhydrides thereof, or
It is also possible to blend polyimide or its precursor, polyamideimide, etc., which are separately synthesized.

Specific examples of diamines include: phenylene diamine, m-phenylene diamine, 3,4°-diaminodiphenyl ether, 4,4°-diaminodiphenyl ether, 4,4′-diaminodiphenylmethane, 3,3
゛-Dimethyl-4,4-diaminodiphenylmethane, 2
,2-bis[4-(4-aminophenoxy)phenyl]
Propane, 1,2-bis(anilino)ethane, diaminodiphenylsulfone, diaminobenzanilide, diaminobenzoate, diaminodiphenylsulfide, 2,
2-bis(p-aminophenyl)propane, 2,2-bis(aminophenyl)hexafluoropropane, 1,
5-diaminonaphthalene, diaminotoluene, diaminobencytrifluoride, 1,4-bis(p-aminophenoxy)benzene, 4.4°-bis(aminophenoxy)biphenyl, diaminoanthraquinone, 4,4°
-bis(3-aminophenoxyphenyl)diphenylsulfone, 1,3-bis(anilino)hexafluoropropane, 1,4-bis(anilino)octafluorobutane, 1,5-bis(anilino)decafluoropentane, 1
．． 7-bis(anilino)tetradecafluorohebutane,
Below - Shipman (However, in the formula, R14 and R16 represent a divalent organic group,
R13 and R15 represent a monovalent organic group, p and q are 1
diaminosiloxane, 2,2-bis[4-(p-aminophenoxy)phenyl]hexafluoropropane, 2,2-bis[4-(3
-aminophenoxy)phenyl]hexafluoropropane, 2,2-his[4-(2-aminophenoxy)phenyl]hexafluoropropane, 2,2-bis[4-(
4-aminophenoxy)-3,5-dimethylphenyl]
Hexafluoropropane, 2,2-bis[4-(4-7
minophenoxy)-3,5-ditrifluoromethylphenyl]hexafluoropropane, Kanobis(4-amino-
2-trifluoromethylphenoxy)benzene, 4,4
-bis(4-amino-2-trifluoromethylphenoxy)biphenyl, 4,4°-bis(4-amino-3-trifluoromethylphenoxy)biphenyl, 4,4°-
Bis(4-amino-2-trifluoromethylphenoxy)diphenylsulfone, 4.4°-bis(3-amino-
5-trifluoromethylphenoxy) diphenylsulfone, 2,2-bis[4-(4-amino-3-trifluoromethylphenoxy)phenylcohexafluoropropane, benzidine, 3.3°, 5.5'-tetramethyl Benzidine, octafluorobenzidine, 3,3"-dimethoxybenzidine, o-tolidine, m-tolidine, 2
, 2°, 5.5', 6.6'-hexafluorotridine, 4,41-diaminoterphenyl, and 4,4111-diaminoquaterphenyl.

Examples of other tetracarboxylic acids and derivatives thereof include the following. Note that, although tetracarboxylic acids are exemplified here, esterified products, acid anhydrides, and acid halides thereof can of course also be used. 3,3
°, 4,4-biphenyltetracarboxylic acid, 3,3",
4,4-benzophenonetetracarboxylic acid, 3,3°,
4,4°-diphenylsulfonetetracarboxylic acid, 2,
3.3',4-diphenyl ether tetracarboxylic acid,
・2,3,3°, 4-benzophenonetetracarboxylic acid, 2.3.6.7-naphthalenetetracarboxylic acid, 1,
4,5.7-naphthalenetetracarboxylic acid, 1,2゜5
．． 6-naphthalenetetracarboxylic acid, 3,3°, 4.4
-diphenylmethanetetracarboxylic acid, 2,2-bis(
3゜4-dicarboxyphenyl)propane, 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane, 3,4,9.10-tetracarboxyperylene, 2.2-bis[4-( 3,4-dicarboxyphenoxy)phenyl]propane, 2,2-bis[4-(3,4
-dicarboxyphenoxy)phenyl]hexafluoropropane, butanetetracarboxylic acid, cyclopentanetetracarboxylic acid, and trimellitic acid and its derivatives.

In the present invention, thixotropy is imparted to the solution containing the polyimide precursor compound synthesized in this way, and the thixotropy coefficient is set to 3 or more,
Preferably, the following method can be mentioned as a method for increasing the number to 4 or more.

That is, the first method is to use at least one type of good solvent and at least one type of poor solvent for the low thermal expansion polyimide precursor compound, thereby developing large thixotropy. Is possible. A good solvent as used herein is one that can dissolve 10 or more of the polyimide precursor compounds in 100 parts by weight of the solution.
-methyl-2-pyrrolidone, N,N-dimethylformamide, de,N,N-diethylformamide, N,N-dimethylacetamide, N,N-diethylacetamide, etc., preferably N,N- Dimethylacetamide or N-methyl-2-pyrrolidone. These solvents may be used alone as good solvents, or two or more types may be used as a mixture.

In addition, a poor solvent is one that dissolves less than 10 parts by weight of the polyimide precursor compound per 100 parts by weight of the solution, and examples thereof include 1-heptene, 2-heptene, 1-octene, 2-heptene, Unsaturated hydrocarbons such as octene and cyclohexene, aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene, ketones such as acetone, butanone, 2-pentanone, 3-pentanone, and cyclohexanone, diethyl ether, and methylpropyl. ether, methyl butyl ether, dipropyl ether,
Ethers such as tetrahydrofuran, 1,3-dioxane, 1,4-dioxane, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol methyl ethyl ether, diethylene glycol dimethyl ether, methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate , propyl acetate,
Methyl propionate, methyl butyrate, methyl valerate, γ-
Examples include esters such as butyrolactone, nitriles such as acetonitrile, acrylonitrile, propionitrile, etc., but are not limited to these. However, saturated aliphatic hydrocarbons are generally unsuitable because they have poor miscibility with the above-mentioned good solvents, and those containing active hydrogen such as alcohols and carboxylic acids inhibit the polymerization reaction of the polyimide precursor compound. Alternatively, it is undesirable because it promotes decomposition reactions.

As the poor solvent used in this case, it is preferable to select one having a lower boiling point than the good solvent, which facilitates lowering the thermal expansion and improves the mechanical properties of the resulting film.

The second method for developing titanium tropism in the polyimide precursor solution includes 1 to 50 parts by weight, preferably 5 to 40 parts by weight, more preferably 10 to 30 parts by weight of the polyimide precursor compound. This is a method of imidizing , and this method also makes it possible to express excellent thixotropy. If the imidization rate at this time is less than 1 part by weight, the imparting of thixotropy will be insufficient, and if the imidization rate is less than 1 part by weight,
If the amount exceeds 1 part by weight, the viscosity of the solution will increase significantly, making it unsuitable as an ink for printing.

Partial imidization of the polyimide precursor compound in advance can be easily carried out by adding a predetermined amount of an acid anhydride such as acetic anhydride and reacting at 30 to 140°C. As a catalyst in this case, a basic compound such as pyridine, picoline, or quinoline can be used.

Furthermore, as a third method for imparting thixotropy, 30 to 200 parts by weight, preferably 50 parts by weight of polyimide powder having a particle size of 20 μs or less, preferably 15 μs or less is added to 100 parts by weight of the polyimide precursor compound. ~
This is a method of blending within a range of 150 parts by weight. Here, if the particle size of the polyimide powder exceeds 20ts, it becomes difficult to develop thixotropy, the mechanical properties of the obtained film decrease, and the blending ratio of the polyimide powder is higher than that of the polyimide precursor. 3 for 100 parts by weight of compound
If it is less than 0 parts by weight, it will be difficult to impart thixotropy, and if it exceeds 200 parts by weight, it will be difficult to achieve low thermal expansion and the mechanical properties of the resulting film will deteriorate.

There are no particular restrictions on the method for producing such a composition in which polyimide powder is contained in a polyimide precursor solution, but the following method can be exemplified, for example.

(2) A method in which a separately synthesized polyimide powder is dispersed in a solvent, a diamine for synthesizing a polyimide precursor compound is dissolved, and a tetracarboxylic acid or a derivative thereof is further added. In this case, the order of addition of the diamine and the tetracarboxylic acid or its derivative may be reversed.

■Synthesize a precursor compound of polyimide powder by solution polymerization, and then heat it to 140 to 300°C to obtain a composition in which polyimide powder is dispersed, and in this composition, the raw material for the polyimide precursor compound A method in which a diamine is dissolved, and then a tetracarboxylic acid or a derivative thereof is added.

In this case as well, the order of adding the diamine and the tetracarboxylic acid or derivative thereof may be reversed.

■A method in which polyimide powder and polyimide precursor solution are synthesized separately and then kneaded using a triple roll or the like.

The resin composition of the present invention is cured by solvent drying and imidization. The solvent drying temperature and imidization temperature at this time can be arbitrarily selected. The imide temperature is usually 200°C or higher, preferably 250°C or higher. In general, it is okay to raise the temperature above the glass transition temperature.

The coating composition of the present invention has both a low coefficient of linear expansion and excellent thixotropy suitable for screen printing, and can form precise patterns without sag or bleeding by directly applying screen printing technology. FP can be easily and inexpensively printed like conventional solder resist printing.
It is possible to apply a coating such as C, etc., and it is possible to provide mechanical properties equivalent to those of FPC laminated with a coverlay film.

The mechanical properties, especially the bending resistance, of the polyimide protective coating thus obtained can be determined by the MIT bending test. This MIT bending test has a thickness of approximately 25I11t
, using a film with a width of 10 m and a radius of curvature of 0°388.

Further, the coating composition of the present invention can be used as a coating material for FPC, IC
It can be used as a coating material for LSI, an alignment film for liquid crystals, and a protective material for electronic components that require pattern formation. Although various methods can be used as the coating method, a coating method using screen printing is particularly excellent. In particular, when used as a covering material for FPC, it maintains the mechanical properties of conventional polyimide while creating a flat, curl-free FP.
C is obtained. The FPC to be removed is preferably heat resistant, and more preferably an adhesive-free type FPC. When an adhesive-free type FPC is used, there is no risk of problems such as a decrease in adhesive strength or carbonization of the adhesive when it is cured at high temperatures.

[Examples] The present invention will be specifically described below based on Examples and Comparative Examples.

The coefficient of linear expansion was measured using a thermomechanical analyzer (TMA) using a sample that had undergone a sufficient imidization reaction.The temperature was raised to 250°C and then cooled at a rate of 10'C/min. Calculating the average coefficient of linear expansion up to C (obtained from

The bending resistance test was carried out using a sample with a width of 10 m and a thickness of approximately 25 mm, and was measured by the MIT rolling fatigue test manufactured by Toyo Seiki Seisakusho.

The thixotropic coefficient was measured using a B-type viscometer.

The abbreviations on each side are as follows.

PMOA: Pyromellitic dianhydride BPD^: 3,3°, 4,4°-biphenyltetracarboxylic dianhydride DDE: 4,4°-diaminodiphenyl ether HABA: 2°-methoxy-4,4′-diamino Benzanilide p-PDA: p-phenylenediamine DHAc: N,N-dimethylacetamide NHP:
N-Methyl-2-pyrrolidone The FPC used in the Examples and Comparative Examples is an adhesive-free type, and its manufacturing method is as follows.

Once, while flowing 200 ml of nitrogen per minute into a 500 ml separable flask equipped with a calcium chloride tube, a reflux condenser, a stirring bar and a nitrogen inlet, IABAI
6. 7'j (0,065mol>, D
DE (0,035mol> and DHAC257g
Add PMOA21, 89 while stirring under cooling.
(0.1 mol) was added. Stirring was continued for about 2 hours at room temperature, and a viscous resin solution was obtained.

Next, this resin solution was applied onto an electrolytic copper foil with a thickness of 35 μIR so that the film thickness was approximately 25 mm, and then
It was left in a forced draft oven at 0°C for 10 minutes for preliminary drying, and then left in a circulation oven at 300°C for 15 minutes to imidize, yielding a flat copper-clad laminate.

Etching resist is applied to the copper foil surface of the thus obtained copper clad laminate in the shape of a circuit by screen printing, and after drying the solvent, etching is performed with a ferric chloride solution, followed by alkaline cleaning and water washing. , and drying to obtain an FPC.

Example 1 While flowing nitrogen at 200 d/min into a 50011iI separable flask equipped with a thermometer, calcium chloride tube, reflux condenser, stirring bar, and nitrogen inlet, p-poA 1
8 g (0.1 mol) of NHP, 114 g of NHP, and 114 g of toluene were added and stirred.

While cooling this solution to below 110°C in a water cooling bath,
When 29.4 g (0.1 mof) of PDA was gradually added, BPD^ reacted while gradually dissolving. Thereafter, stirring was continued at room temperature for about 2 hours to carry out polymerization, and the solution gradually became viscous, then became cloudy and became opaque.

The resulting resin solution had a thixotropy coefficient of 5°8, and the droop width during screen printing was as small as 100 p or less.

This resin solution was applied onto Pyrex glass to a film thickness of approximately 251E1, and heated at 100°C and 150°C.
Preliminary drying was performed by leaving each sample in a forced air oven at 300°C for 10 minutes, and then imidization by leaving it in a circulating hot air oven at 300°C for 15 minutes.

After cooling, it was peeled off to obtain a film.

The coefficient of linear expansion of this film is 5 x 10-6 (1/K
), and the bending resistance according to the MIT bending test is 10°0
It was more than 00 times.

Furthermore, when it was applied onto an FPC and cured, a substantially flat surface was obtained.

Example 2 Similar to Example 1, IABAI was placed in a separable flask.
6,7 g (0,065 mol), DDE 7.0 g
(0,035 mof), DHACl 559.103 g of 4-methyl-2-pentanone were added, and PMOA 21°89 (0.1 mol>) was added while stirring under cooling. After stirring at room temperature for about 1 hour, it became viscous. A cloudy resin solution was obtained.

The thixotropy coefficient of this resin solution was 4.2, and the droop width in screen printing was 100u11.

The linear expansion coefficient of the obtained film was 8X 10' (17
), and the bending resistance according to the MIT bending test was 10.
It was more than 000 times.

Furthermore, when it was applied onto an FPC and cured, a substantially flat surface was obtained.

Example 3 Similarly to Example 1, HABA7.
1 g, D[)E 4.5 g, NHP 54.5 g and diglyme 81. of PMOAl while stirring under cooling.
Added 0.59. After reacting at room temperature for about 1 hour, add 9.5 g, PMOA 7.9 g, NMP23 to the colander H^8.
．． 3 g of diglyme and 35.0 g of diglyme were added thereto, and stirring was continued at room temperature for about 3 hours, and the resin solution gradually became viscous and cloudy.

The thixotropy coefficient of this resin solution is 11, and the droop width during screen printing is 100 IJ! It was 1 or less.

The coefficient of linear expansion of the film is 9 x 1()-6(t/K)
The bending resistance according to the MIT bending test is 10.00.
It was 0 or more times.

Furthermore, when it was applied onto an FPC and cured, a substantially flat surface was obtained.

Example 4 Similar to Example 1, HABA14 was placed in a separable flask.
．． 2 g, DDE 9.0 g, NMP 87.9 g and diglyme 163.2 g, and while stirring under cooling, PM
2 g of OA21 was added. When the reaction was carried out at room temperature for about 2 hours, a transparent and uniform resin solution A which gradually became viscous was obtained.

Separately, in the same manner as in Example 1, 25.7 g of fA8A, 65.6 g of NHP, and 121.9 g of diglyme were added to a separable flask, and while stirring under cooling, PMOA
21.2 g was added. While stirring was continued at room temperature, this resin solution gradually became viscous and then became cloudy, and finally became a lump-like composition B.

Next, equal weights of resin solution A and composition B were taken and kneaded using three rolls to obtain composition C.

The thixotropic coefficient of this composition C was 8.9, and the droop width by screen printing was 100 μs or less.

The coefficient of linear expansion of the film is IOX 10"6 (1/2), and the bending resistance according to the MIT bending test is 10,000
It was more than once.

When this composition was applied onto an FPC and cured, a substantially flat surface was obtained.

Example 5 Similar to Example 1, HABA25 was placed in a separable flask.
．． 7 g, DHACl 87 g, acetonitrile 125
g and 29.49 BPDA was added while stirring under cooling. After stirring at room temperature for about 3 hours, the mixture gradually became viscous and cloudy.

The thixotropy coefficient of this resin solution is 5.4, and the droop width in screen printing is 100 IJj! It was 1 or less.

The linear expansion coefficient of the obtained film was 18X 10-6 (1
/K), and the bending resistance according to the MIT bending test is 10
It was more than ゜000 times.

Furthermore, when it was applied onto an FPC and cured, gentle curling occurred with the protective layer on the inside, but this was enough to cause no problem in practical use.

Example 6 Similarly to Example 1, p-PDAI was placed in a separable flask.
228 g of o, l, NHP were added, and 29.4 g of BPDA was added while stirring under cooling. After reacting at room temperature for about 2 hours with stirring, a viscous and uniform resin solution was obtained.

Next, 2.1 g of acetic anhydride and 2.1 g of β-picoline were added to this resin solution. After adding Og and continuing stirring for about 30 minutes, the temperature was raised to 50° C. with further stirring, and the resin solution became reddish in color and its viscosity increased.

The titanium tropy coefficient of the resulting resin solution was 3°6, and the droop width during screen printing was less than 100 mm.

The coefficient of linear expansion of the film is 7 x 10-6 (1/K), and the bending resistance according to the MIT bending test is 10,000
It was more than once.

When it was applied onto FPC and cured, an almost flat surface was obtained.

Example 7 As in Example 1, iABA1 was added to a separable flask.
6.7 g, DDE 7.09 were added, and while stirring under cooling, P)lDA21,89 was added. The reaction was carried out with stirring at room temperature for about 3 hours to obtain a viscous and homogeneous resin solution.

Next, 6.2 g of acetic anhydride and 2.2 g of β-picoline were added to this resin solution. After adding Og and continuing stirring for about 30 minutes, the temperature was raised to 50° C. with further stirring, and the resin solution became reddish in color and its viscosity increased.

The resulting resin solution had a thixotropy coefficient of 9°6, and the sagging width by screen printing was 100p or less.

The coefficient of linear expansion of the film is 10X 1O-6 (1/2), and the bending resistance according to the MTT bending test is 10,000
It was more than once.

When it was applied onto FPC and cured, an almost flat surface was obtained.

Example 8 Similar to Example 1, add HABA2 (in a separable flask)
5.1 and 269 g of DHAC were added, and while stirring under cooling, 21.8 g of PHDA was added. After reacting at room temperature for about 2 hours, a viscous and uniform resin solution was obtained.

Next, when this resin solution was heated to 150° C. with stirring, the liquid began to become cloudy and polyamide-imide powder was precipitated. After continuing to stir for about 1 hour,
The slurry containing this polyamide-imide powder was taken out, filtered, washed, and dried to obtain polyamide-imide powder.

This polyamide-imide powder has a weight average particle diameter of 3゜4*,
The maximum particle size is 10x or less and the density is 1.459/cm3
Met.

Next, put this polyamide-imide powder 4 into a separable flask.
After adding 0g of HABAI and 257g of DHAC and thoroughly dispersing the polyamideimide powder, 5.7g of HABAI and 7g of Oko were added. Og was dissolved. Thereafter, 21.7 g of PHD was added while stirring while cooling, and the reaction was carried out at room temperature for about 2 hours while stirring, to obtain a viscous composition.

The resulting resin solution had a thixotropy coefficient of 7°6 and a droop width of 100p or less during screen printing.

The linear expansion coefficient of the film is 17X 10-6 (1/K), and the bending resistance according to the MIT bending test is 5,000
It was more than once. As long as it has this level of bending resistance, there is no problem in practical use.

When it was coated on FPC and cured, gentle curling occurred with the protective layer on the inside, but this was enough to cause no practical problems.

Example 9 Similar to Example 8, p-PDA 5 , 4 g, NHP
Using 14 g of 'l' and BPDAl 4 , 69, the weight average particle size was 2.44. A slurry containing polyimide powder having a maximum powder diameter of 8IIR or less was obtained.

Next, after cooling this slurry to room temperature, 8°4g of HABA was added.
, DDE 7.09 and NMP 129g, HAB
After dissolving A and 0 leaves, PM while stirring under cooling.
0.9 OAl was added. When the reaction was carried out at room temperature with stirring, a viscous composition was obtained.

The resulting resin solution had a thixotropy coefficient of 6°4 and a droop width of 100p or less during screen printing.

The coefficient of linear expansion of the film is 19x 1O-6 (1/2), and the bending resistance according to the MIT bending test is 10.000.
It was more than once.

When it was coated on FPC and cured, gentle curling occurred with the protective layer on the inside, but this was enough to cause no practical problems.

Example 10 Same as Example 8, p-PDA 10.89, NHP
Using 2289 and BPD^29.2g, the weight average particle size was 2.3u! A polyimide powder having a maximum particle size of 8 InR or less was obtained.

Separately, in the same manner as in Example 1, HABAI 6, 79, 14.0 g of DDE, and NHP were added to a separable flask.
2579 and PHDA211.89 were charged and reacted to obtain a viscous and uniform resin solution.

Next, polyimide powder 309 and 200 g of the resin solution were kneaded using a triple roll to obtain the desired composition.

The resulting resin solution had a thixotropy coefficient of 8.9 and a droop width of 100 μm or less during screen printing.

The linear expansion coefficient of the film was 14 x 10' (1/K), and the bending resistance according to the MIT bending test was 7,000 times or more. As long as it has this level of bending resistance, there is no problem in practical use.

When it was applied onto FPC and cured, an almost flat surface was obtained.

Comparative Example 1 Similar to Example 1, 1 (ABAl 6.7!?, DD
E7゜Og, DHAc257g and PMDA21,
89 to obtain a uniform and viscous resin solution.

The coefficient of linear expansion of the cured and jqed film is 8×10−
6 (1/K), the bending resistance according to the MIT bending test is 1
0,000 times or more, the thixotropy coefficient of the resin solution was as small as 1.5, and the droop width during screen printing was as large as 300- or more.

Comparative Example 2 Same as Example 1, DDE 20.0g, DHAC94.7
9,1-Luene 142.19 and PMOA21,8
A viscous and cloudy resin solution was obtained using g.

The resulting resin solution had a thixotropy coefficient of 6°3 and a droop width of 10011 m or less during screen printing.

However, the coefficient of linear expansion of the film is 25X 1O-6 (1
/K), and when it was applied and cured on FPC,
Large curls occurred with the protective layer inside.

[Effects of the Invention] The coating composition of the present invention has excellent screen printability, low thermal expansion, and excellent bending resistance.
For example, it is extremely useful as an industrial material for coating electronic material components such as printed circuit boards, especially flexible printed circuit boards.

Patent applicant: Nippon Steel Chemical Co., Ltd.

Claims (10)

[Claims] (1) Linear expansion coefficient after curing is 20 x 10^-^6 (1/
K) A coating composition comprising the following polyimide precursor compound and having a thixotropy coefficient of 3 or more. (2) The polyimide precursor compound has the following general formula (II) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (II) (However, in the formula, R5 to R12 are hydrogen, halogen,
Indicates any group selected from a lower alkyl group and a lower alkoxy group, among which at least one of R7 to R10 is a lower alkoxy group, and Ar is represented by the formula ▲,
A coating composition characterized in that it is a polyamide-imide precursor containing a structural unit represented by either ▼ or ▲ or ▼. (3) The coating composition according to claim 2, wherein the polyimide precursor compound is a polyamide-imide precursor containing a structural unit represented by the following formula (III) ▲ Numerical formula, chemical formula, table, etc. ▼ (III) . (4) The polyimide precursor compound has the following general formula (I) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (I) (However, in the formula, R1 to R4 are hydrogen, halogen, lower alkyl group, and lower alkoxy group, respectively. A coating composition characterized in that it is a polyimide precursor containing a structural unit represented by any selected group. (5) At least 1
5. The coating composition according to claim 1, comprising at least one type of good solvent and at least one type of poor solvent. (6) The coating composition according to claim 5, wherein the poor solvent has a lower boiling point than the good solvent. (7) The coating composition according to any one of claims 1 to 6, wherein 1 to 50 parts by weight of the polyimide precursor compound is imidized. (8) The coating composition according to any one of claims 1 to 6, wherein 30 to 200 parts by weight of polyimide powder having a particle size of 20 μm or less is blended to 100 parts by weight of the polyimide precursor compound. (9) The film obtained by curing was 1 in the MIT bending test.
9. The coating composition according to claim 1, which has a bending resistance of 0,000 times or more. (10) The linear expansion coefficient after curing is 20×10^-^6(1
/K) Contains the following polyimide precursor compound, and
A coating composition with a thixotropy coefficient of 3 or more is used, and this is applied to the surface of a printed circuit board with electronic circuits and other wiring by screen printing, and after drying, the polyimide precursor compound is cured and printed. 1. A method of using a coating composition characterized by forming a polyimide protective film on the surface of a substrate.